Definition
A Latin phrase meaning "from or arising out of wrongdoing." Ex maleficio describes obligations, liabilities, or legal consequences that grow out of a tortious act, misconduct, or illegal conduct — as distinguished from obligations arising out of agreement. In classical usage, the term functions as a near-synonym for ex delicto and stands in contrast to ex contractu.
The phrase carries a second, closely related sense captured in the maxim ex maleficio non oritur contractus: a contract cannot arise out of an act that is fundamentally vicious or illegal. This principle bars a party from converting an unlawful act into an enforceable contractual right simply by framing it in contractual terms.
Common Confusion
Ex maleficio and ex delicto are often treated as interchangeable, and for most purposes they are. Both describe obligations or actions arising from wrongful acts rather than agreements. The distinction is one of emphasis and origin: ex delicto is the more common common-law formulation, while ex maleficio appears more frequently in civil-law texts and in early authorities such as Bracton. Researchers should not read substantive legal difference into an author's choice between the two terms — the choice typically reflects the writer's training, the era, and the tradition being cited rather than a meaningful doctrinal gap. A third term, ex quasi ex delicto (or quasi ex maleficio), sometimes appears in civil-law discussions to describe obligations that resemble tort liability but arise without a technically wrongful act; this is a distinct category and should not be conflated with ex maleficio proper.
Why It Matters in Research
The primary research trap is chronological: ex maleficio is predominantly a civil-law and early common-law term. It appears in Bracton and in Roman-law-influenced texts but recedes sharply in mainstream English common-law materials from the seventeenth century onward. A researcher encountering ex maleficio in a post-medieval common-law source should treat it as a deliberate civil-law or comparative-law reference, not standard terminology.
The maxim ex maleficio non oritur contractus has independent doctrinal life. When researching the unenforceability of contracts founded on illegal acts — what modern law addresses through doctrines of illegality and public policy — historical sources may invoke this maxim rather than the modern terminology. Researchers working backward from contemporary illegal-contract doctrine into historical materials must know to search for this phrase and its variants.
Because the term belongs to the civil-law taxonomy of obligations, it appears most naturally in sources organized around the Roman-law division: ex contractu, ex maleficio (or ex delicto), and quasi-categories. When a historical treatise or encyclopedia uses this tripartite structure, ex maleficio is carrying the weight of the entire law of tort-based obligation — a far broader function than the phrase's literal simplicity suggests.
Jurisdictional variation is relevant at the level of legal tradition, not geography: civilian jurisdictions (and mixed jurisdictions such as Louisiana and Scotland) will use ex maleficio or ex delicto more naturally and more frequently than pure common-law jurisdictions, where ex delicto itself is the rarer choice and modern terminology — tort, wrongful act, delict — dominates.
Historical Dictionary Support
The four source dictionaries agree on substance while reflecting different emphases. Burrill's is the most precise, correctly identifying ex maleficio as the civil-law term of preference over ex delicto, citing the Institutes and Digest directly (Inst. 3.14.2; Inst. 4.1 pr.; Dig. 44.7.4), and noting Bracton's adoption of the phrase. Black's (both editions) confirms the civil-law origin and the contrast with ex contractu, likewise noting the Bracton citations and the relative rarity of the term in common-law usage. Rapalje & Lawrence offer only a compressed gloss — "on account of misconduct, or a tort" — without the civil-law context, which is a meaningful omission for researchers who need to understand why the term appears where it does in historical sources.
None of the historical sources fully develops the maxim ex maleficio non oritur contractus beyond a single sentence. Researchers seeking the doctrinal application of that principle will need to look beyond dictionary entries to treatise literature on contract illegality.
What the historical dictionaries collectively miss is the connection between ex maleficio and the quasi-contractual or restitutionary doctrines that occupied civilian jurists. The civil-law taxonomy of obligations had four heads — ex contractu, quasi ex contractu, ex maleficio, quasi ex maleficio — and the last two together constituted the law of non-consensual obligations. Dictionary entries that treat ex maleficio in isolation give an incomplete picture of how the term functioned within that broader framework.